Correlations in the Electronic Structure of van der Waals NiPS$_3$ Crystals: An X-Ray Absorption and Resonant Photoelectron Spectroscopy Study

TL;DR

This study combines advanced spectroscopy and DFT calculations to analyze the electronic structure of NiPS₃ crystals, revealing their charge-transfer insulator nature and implications for electronic and spintronic applications.

Contribution

It provides a detailed element-specific analysis of NiPS₃'s electronic structure using NEXAFS, ResPES, and DFT, identifying it as a charge-transfer insulator for the first time.

Findings

NiPS₃ is identified as a charge-transfer insulator.

Spectroscopic data align with DFT calculations.

Insights into electron correlations in layered transition-metal materials.

Abstract

The electronic structure of high-quality van der Waals NiPS$_3$ crystals was studied using near-edge x-ray absorption spectroscopy (NEXAFS) and resonant photoelectron spectroscopy (ResPES) in combination with density functional theory (DFT) approach. The experimental spectroscopic methods, being element specific, allow to discriminate between atomic contributions in the valence and conduction band density of states and give direct comparison with the results of DFT calculations. Analysis of the NEXAFS and ResPES data allows to identify the NiPS$_3$ material as a charge-transfer insulator. Obtained spectroscopic and theoretical data are very important for the consideration of possible correlated-electron phenomena in such transition-metal layered materials, where the interplay between different degrees of freedom for electrons defines their electronic properties, allowing to understand their optical and transport properties and to propose further possible applications in electronics, spintronics and catalysis.